1. Field of the Invention
The present invention relates to an electric wire connector which is attached to an end of a signal cable.
2. Description of the Related Art
One end of a conventional coaxial cable for transmitting a signal, electric power, or the like is provided with a coaxial cable connector to allow the coaxial cable to be connected and disconnected. Such a coaxial cable connector is constructed primarily by an inner conductor, an insulating member disposed around the inner conductor, and an outer conductor disposed around the insulating member. The inner conductor and the outer conductor of the coaxial cable connector are connected to a core and a shielding wire, respectively, of the coaxial cable.
The three members, namely, the inner conductor, the insulating member, and the outer conductor, of the coaxial cable connector must be fixed with sufficient strength in the connecting and disconnecting directions to survive frequent connection and disconnection.
Hence, in the conventional coaxial cable connector, of the three members, i.e. the inner conductor, the insulating member, and the outer conductor, the insulating member and the outer conductor are plastically or elastically deformed by applying external force to secure fixing force, so that all the members are fixed firmly to survive the connection and disconnection.
The coaxial cable connector disclosed in the Publication of Japanese Utility Model No. 61-21811, for example, has the following construction: the inner conductor equipped with a tapered projection, which has a larger diameter than that of a through hole provided along the central axis of the insulating member, is fixed with pressure in the through hole of the elastic insulating member. The internal circumference of the outer conductor is provided with a tapered section and the aforesaid elastic insulating member is held and fixed with pressure onto the tapered section.
The coaxial cable connector, however, is repeatedly subjected to connection and disconnection; therefore, the inner conductor must be firmly fastened with the insulating member or the outer conductor. For this reason, in order to improve the strength of fixing the inner conductor to the insulating member in the connector for coaxial cable disclosed in the Publication of Japanese Utility Model No. 61-21811, it is necessary to make a design change such as increasing the diameter of the tapered projection of the inner conductor and employing a hard material with a large Young's modulus for the insulating member.
In the coaxial cable connector disclosed in the Publication of Japanese Utility Model No. 61-21811, however, the tapered projection stretches the through hole in the insulating member as the inner conductor of the coaxial cable connector is inserted. This structure has a drawback in that the improvement in the fixing strength made by the design change described above is limited and it is difficult to accomplish the fixing strength which is sufficient to survive highly frequent connection and disconnection.
Furthermore, since the tapered projection deforms the through hole in the insulating member when inserting the inner conductor, the insulating member cannot fully restore its shape to fit itself tightly around the contour of the tapered projection unless the insulating member is made of a sufficiently flexible material. Hence, the area of the contact between the tapered projection and the insulating member, which cannot fully restore its original shape, undesirably decreases from a designed value of area, leading to the difficulty of securing adequate fixing strength.
In addition, the inner conductor has a stopper with a large outside diameter and the stopper is applied to the side surface of the insulating member to position it. This, however, makes it difficult to decide whether the inner conductor has fully been press-fitted in the insulating member since an elastic member is used for the insulating member which exhibits low resiliency. Therefore, the stopper sometimes undesirably goes too far into the insulating member, presenting a problem in addition to the difficulty in determining incomplete press-fitting. Thus, the structure presents another shortcoming, that is, the difficult positioning of the inner conductor in relation to the insulating member.
The shortcomings stated above are encountered not only when press-fitting the inner conductor into the insulating member; they are encountered also when press-fitting the insulating member into the outer conductor. The press-fitting is involved in the assembly of the inner conductor and the insulating member and also in the assembly of the insulating member and the outer conductor, leading to a problem in that the assembly of the coaxial cable connector takes much time and labor.